I HAD A SIMILER THING WITH A JILL AND IT WAS A ABSES UNFORTUNATLY I LOST HER BECAUSE IT WAS NOT VISABLE AND GREW INWARDS AND SUFERCATED HER SO I WOULD GET YOUR HOB LOOKED AT BY A VET IF U WANT IT TO LIVE.
IF IT IS AN ABSES THE VET WILL PROBLEY DRAIN IT THERE AND THEN ITS NOT AN EXSPENSIVE DO